For this reason the first injection is usually given during the first 1-5 days of a period. If you have the injection within five days of starting a period, you will be protected immediately. Further injections are then given up to 13 weeks apart, depending on the type used. If you are unable to make an appointment within that five-day window, you can have the injection at any time, as long as you are reasonably sure you are not pregnant. Your practice nurse or doctor will advise you to use extra contraception (such as a condom) for seven days after the injection. This is what is called an "off-label use" and not all practices will allow it.
You can use SQL views to further increase the granularity of access by limiting the read access to specific fields of a table or joins of tables. It could potentially have additional benefits: for example, suppose that the system is required (perhaps due to some specific legal requirements) to store the passwords of the users, instead of salted-hashed passwords. The designer could use views to compensate for this limitation; revoke all access to the table (from all DB users except the owner/admin) and create a view that outputs the hash of the password field and not the field itself. Any SQL injection attack that succeeds in stealing DB information will be restricted to stealing the hash of the passwords (could even be a keyed hash), since no DB user for any of the web applications has access to the table itself.